A conventional dispenser head, e.g. of the pusher type, comprises:                an inlet well for connecting to an outlet of a dispenser member, such as a pump or a valve;        an axial assembly housing in which there extends a pin defining a side wall and a front wall; and        a cup-shaped nozzle comprising a substantially-cylindrical wall having an end that is closed by a dispenser wall that forms a spray orifice, the nozzle being assembled along an axis X in the axial assembly housing, with its cylindrical wall engaged around the pin, and its dispenser wall in axial abutment against the front wall of the pin.        
In general, the inlet well is connected to the axial assembly housing via a single feed duct. In addition, it is common to form a swirl system in the dispenser wall of the nozzle. A swirl system conventionally comprises a plurality of tangential swirl channels that open out into a swirl chamber that is centered on the spray orifice of the nozzle. The swirl system is disposed upstream from the spray orifice.
In addition, it is also common practice to make the nozzle in such a manner as to be circularly symmetrical around the axis X. Thus, it is not necessary to orientate the nozzle relative to the housing. Naturally, that implies that all of the swirl channels are not oriented in the same manner relative to the feed duct connecting the inlet well to the assembly housing. By way of example, one swirl channel may be disposed substantially extending the feed duct, while the other two or three swirl channels are not fed directly by the feed duct. That means that the swirl channels are not fed in identical, uniform, or symmetrical manner, with one swirl channel being more favored, and another swirl channel being less favored.
In the prior art, document EP-0 802 827 describes a particular dispenser head including two parallel feed ducts that open out into an axial assembly housing that receives a very particular nozzle of oblong shape. The dispenser head of that document makes it possible to satisfy certain particular requirements, in particular with regard to the size of the nozzle, that is of a size not much greater than a grain of rice. However, the size and the configuration of that particular nozzle create serious drawbacks. Firstly, it is not easy to take hold of the nozzle, as a result of its oblong shape. Then, it is essential to orientate the nozzle in such a manner as to present it correctly in front of the assembly housing, which is itself also oblong. Finally, it is not easy to insert the nozzle into its housing, mainly as a result of the nozzle being substantially flat. The nozzle comes into contact with a core 11 that forms an end wall of the axial assembly housing. The core is formed with a swirl system that comprises two tangential channels that open out into a central swirl chamber. On either side of the core there extend the two feed ducts that connect to the inlet well. In the design in that document, the oblong and flat nozzle penetrates into the axial assembly housing in such a manner as to come into leaktight contact with the core, but without penetrating into the lateral feed ducts. As a result, the nozzle is held in the assembly housing only at its outer periphery that is advantageously made in beveled manner so as to form an assembly edge for coming into engagement in the side wall of the assembly housing.
It is easy to understand that that particular dispenser head is difficult to assemble in industrialized manner, thereby considerably increasing its cost price.
However, an advantage of that particular dispenser head is that the swirl channels of the swirl system are fed in symmetrical manner by the two feed ducts that connect to the inlet well. Thus, each swirl channel is fed by its own feed duct. In addition, the feed ducts and the swirl channels are disposed in completely symmetrical manner relative to the swirl chamber, so that each feed duct and each swirl channel is fed in strictly identical manner with fluid coming from the inlet well. Such feed symmetry is indeed achieved with the dispenser head of document EP-0 802 827, but with considerable drawbacks associated with the shape of the nozzle and of the axial assembly housing.